[fprint] Linux Mint 16 w/ Targus PA460 (AES4000)

[David Albert]

I am trying to get a Targus PA460 capacitive fingerprint scanner 
(Authentec aes4000 driver) working with fprint and have had mixed (but 
generally unacceptable) results.  I am running Linux Mint 16.

I tried first with the stock Linux Mint binary packages and although the 
scanner is always recognized, I was unable to enroll a finger; after the 
first scan, fprintd would stop responding; other users have reported the 
same problem.  I have 4 scanners and they all behave identically.  When 
running fprintd -t in a console so I can see the results, the daemon 
shows no activity when the fprintd-enroll task requests a rescan.

I rebuilt from source using libfprint-0.5.1 and fprintd-0.5.1 and the 
results were better.  I was able to get fingerprints enrolled using 
fingerprint-gui, but it is very flaky and crashes frequently crashes.  
With fprintd-enroll I was also able to enroll my right index finger 
only.  fprint-verify sometimes verifies successfully, but it generally 
fails.  There is also a serious defect in that if a scan fails, it will 
not retry and the client app (enroll or verify) must be killed to resume 
scanning (see defect reports below).

I realize the PA460 is a poor scanner (250dpi, 10mm square, 96x96 
pixels), but one problem may be contrast; fprint_demo shows the captured 
images and they have extremely light contrast; I have seen images 
captured by fprint_demo with other scanners and they show high contrast 
between ridges and grooves.  I tried increasing the sensor gain 
(libfprint/drivers/aes4000.c:94) from 0x23 to 0x33 and the results 
seemed to improve.  I found the hardware manual and non-official linux 
USB driver source here: 
http://sourceforge.net/projects/aes4kusbdriver/   I'll read it and 
experiment some more, to see if I can get better results.

Any help/suggestions would be appreciated, the PA460 is basically 
unusable in its current state because it rarely verifies an enrolled 
print.  I have extra PA460s and can donate one to a project maintainer 
if there's interest.  Also, please see defect reports below.

Thanks!


Defect: if fprintd-verify shows "Verify result: verify-retry-scan (not 
done)", fprintd-verify will not respond further until it is killed via 
SIGINT.  fprintd continues running properly.

     Client shows:
         ~ $ fprintd-verify
         Using device /net/reactivated/Fprint/Device/0
         Listing enrolled fingers:
          - #0: right-index-finger
         Verify result: verify-retry-scan (not done)

     Daemon shows:
             ~ $ sudo fprintd -t
             Launching FprintObject
             ** Message: D-Bus service launched with name: 
net.reactivated.Fprint
             ** Message: entering main loop
             ** Message: user 'dalbert' claiming the device: 0
             ** Message: now monitoring fd 16
             ** Message: device 0 claim status 0
             ** Message: adding finger 7 to the gallery
             ** Message: start identification device 0
             ** Message: identify_cb: result verify-retry-scan (100)


Defect: the cancel button does not work for the Authenticate dialog for 
fprintd-enroll

Enhancement request: add option to display version.

P.S. I'm a very experienced C/C++ (mostly embedded systems) programmer; 
is the project open to adding developers?

References:
     http://www.datasheetarchive.com/AES4000-datasheet.html
     http://sourceforge.net/projects/aes4kusbdriver/